...the other one requires a bit of patience (secret dynamite one...
Heh - one of the first few achievements I got in the game, that one.
Wasn't deliberate, though (and I've not actually looked through the achievements list). Saw a baddie, shot at him, and just happened to hit a stick of dynamite he was chucking at me.
Don't think I'll be getting many achievements though. I'm not enjoying the game anywhere near as much as I did the old Tomb Raider games.
It's okay, and it's totally beautiful compared to the old stuff - but I don't like all the QTEs* (there's a lot less once you get past that first hour or so, but there's still way too many for my taste) and I've not been anywhere near as fastidious as I usually am - I've not really found many tombs, and I'm sure I've missed loads of other collectibles etc.
I think I'm about three quarters of the way through the game, and only have 210/1000 gamerscore...
*Of course, Tomb Raider games have always had QTEs - but I didn't hate them as much back then as I do now.